In an era that’s witnessed a brief but terrifying Ebola epidemic, the resurgence of yellow fever and dengue, and the emergence of wholly new diseases like Chikungunya, the Zika virus remains uniquely frightening: It’s the first infectious disease in 60 years to cause birth defects, and the first mosquito-borne disease ever to do so.

The virus has spread to more than 50 countries around the world and it is both asymptomatic (in adults) and potentially deadly (in developing fetuses). As we close in on a year of battling this scourge, Consumer Reports spoke with Thomas Frieden, M.D., Director of the Centers for Disease Control and Prevention, at his office in Atlanta about how the lessons of Zika will shape the future of infectious disease control.

(This interview has been condensed and edited.)

The Big Picture

Consumer Reports: What are the key takeaways as this mosquito season draws to a close?

Thomas Frieden, M.D.: There are generic lessons, and Zika-specific lessons. The most important generic lesson is that we need to be better prepared for infectious disease and other health threats. That’s what we mean by global health security: Every country needs to be ready to find, stop and prevent health threats. And when a country’s capacities are overwhelmed, the world needs to be able to surge in more rapidly.

CR: How do we accomplish that?

TF: We’ve already made great strides, but the bottom line is that we need a rapid response fund; we need to have money on hand. When there’s an earthquake, FEMA doesn’t say ‘Congress, will you give us the money?’ They have resources. Sometimes with a really terrible disaster, like Sandy, the World Trade Center, some others, you go to Congress for even more. But at least you’re able to get a running start with the money that you’ve got, without having to rob other programs and juggle things administratively.

We also have to have the authority to act. People are frustrated with us. ‘Why aren’t you getting the money out right away?’ Well, we don’t have emergency authority. We have to go through a 30-day posting process to get money some place. And that’s when an exception is granted; otherwise it takes 60 to 90 days.

CR: What’s your existing budget for emergencies, and which programs did you have to “rob from” to deal with Zika?

TF: In a budget of $14 billion, I have just $2.5 million for emergencies. And to deal with Zika, we had to cut back on HIV prevention, on immunization programs, and on Ebola funding. We also had to take some of the money that we normally would have given out to other states and divert it to the states that needed it most for Zika.

CR: Is it fair to say that diseases spread by mosquitoes and other vectors are becoming more common?

TF: Our Emergency Operations Center has been activated 91% of the time that I’ve been director. So it’s fair to say that this is the new normal. We expect to see a new outbreak every year. And we are launching new investigations once a day, on average. And the reasons for that are plain. More global travel, more urbanization, and in some cases climate change, though climate is complex.

The Lessons of Zika

CR: What are the Zika-specific lessons of the past year?

TF: The first Zika-specific lesson is that we need better mosquito-control technologies. We need to know how to mix and match our existing tools. And we need to develop new ones. We have been able to control Zika in the U.S., in Florida. But in Puerto Rico and in other tropical environments, we don’t yet have the tools.

The second Zika-specific lesson is just the importance and challenge of supporting reproductive health. This was totally unprecedented. We’ve never had a mosquito-born disease that can cause a birth defect. And it’s been nearly 60 years since any infectious disease caused a birth defect [Congenital Cytomegalovirus (CMV) was discovered in 1960; later that decade, the Rubella virus (German Measles) reached pandemic levels in the U.S. and Europe. Both pathogens can cause severe birth defects in the developing fetus].

CR: What do you want the public to understand about Zika?

TF: That answers are going to take time; and we need realistic expectations of what can be figured out when. Sometimes I think we’re victims of our own success. We eradicated smallpox. We’re on the cusp of eradicating polio. We’ve saved hundreds of millions of lives. But it’s as if we say to all the engineers, “Hey, why aren’t we all flying around in Jet Packs?” It takes time to do these things.

Even to do the studies. What are the risk factors for microcephaly? We know that not all mothers who are infected with Zika—even in the first trimester—give birth to babies with microcephaly. It looks like it’s maybe 5-10%. Why is that and what can we learn from it? Well, to study it rigorously, we have to enroll women before the first trimester, then follow them through the entire pregnancy, taking blood from them every two weeks to know if and when they’re infected, because they won’t show symptoms. And then we have to follow their children for five years to see who’s going to be affected and how. These are not quick things.

CR: Many people still aren't following official guidelines when it comes to protecting against mosquito bites. For example, they use natural repellents because it seems safer to them. How do we solve that problem?

TF: We try at CDC to state our positions without overstating them, and to promote awareness through media and social media. For insect repellents we only recommend things that have been registered by the EPA, because those are the things that have been independently analyzed.

But we do have the challenge where some people, especially younger people, think everything online is equally valid. That’s why we value independent groups like Consumer Reports that are not government, but are widely trusted, and will look at the science. And we won’t always agree with each other, but that’s an important function. 

CR: Citizens in both Florida and Puerto Rico have protested the spraying of the pesticide Naled, even as it’s become clear that in Wynwood [a neighborhood in Miami], the chemical was able to reduce mosquito populations and quell the spread of Zika. Did the protests surprise you?

TF: One thing I learned as Health Commissioner of New York City, is that there will always be some groups for whom you’re spraying too much, and there will always be some groups for whom you’re spraying too little. So you have to try to do the right thing, and you have to explain what you’re doing. And nobody likes to use pesticides. We would be delighted if we never had to use pesticides. It’s always going to be a risk and a benefit. And we want to be up front about what the risks are.

What has kind of surprised me, is people like the Mayor of San Juan saying ‘well it might hurt babies, but I have to care about everyone.’ I understand that statement, but it’s really misguided.

CR: The CDC shipped Naled to Puerto Rico and tried to launch an aerial spray campaign there, but was rebuffed by island officials following citizen protests. In retrospect is there anything you would have done differently? [The CDC provides funding and technical expertise to states and cities confronting disease outbreaks and other health crises, but it does not have the authority to compel officials to adopt its recommendations]. 

TF: I don’t know if there’s anything we could have done that would have changed the outcome this year. Certainly we tried. One thing we’re doing now is helping them establish a Puerto Rican Vector Control Unit. They’re the only place in the United States with mosquito diseases and no mosquito control program. So we’ll fund it and we’ll provide the technical support and it will be a Puerto Rican entity with a Puerto Rican community advisory board. And they can make their own decisions about which technologies to try.

The Future of Mosquito Control

CR: You’ve called Aedes aegypti, the mosquito that carries Zika, the “cockroach of mosquitoes.” Tell us a bit about why this bug is so hard to conquer.

TF: They can breed in just a bottle cap’s worth of water—so eliminating breeding sites is extremely labor intensive. They bite four or five people in a single blood meal, and you don’t feel their bites the way you feel other mosquitoes’ bites. Also, they're highly resistant to insecticides.

CR: Insecticide resistance has emerged as a significant barrier to combating Zika. Permethrin resistance in particular concerns us, because that’s one chemical that’s used not only by public health officials, but also in consumer products, including sprays and pre-treated clothing.

TF: [Permethrin and its chemical cousins] have a better risk profile than the others, but resistance is real and growing. So we didn’t put permethrin products in the Zika prevention kits in Puerto Rico, because we didn’t want people putting it on their clothes when it wasn’t going to work. And we’re seeing a fair amount of resistance in other places as well now. But it’s remarkably patchy: mosquitoes are resistant on one block but not on the next. So it’s tough to gauge the utility of those products in any specific place.

What’s clear is that we need to find new classes of insecticides because we are running out [of chemicals that work].

CR: What are some of the most promising things you see coming through the pipeline?

TF: Nootkatone is very promising. So about a decade ago, a Native American shaman came to our Fort Collins office saying that he knew the bark of a certain tree repelled ticks and other disease-causing insects, and he was dying and he wanted this knowledge passed on to benefit humanity. So they spent years identifying the chemical within the tree and figuring out how to produce it industrially. Turns out—nootkatone—it smells faintly of grapefruit.

We’ve commercialized it and with the Zika money we’re trying to move it to the market fast. It could be used potentially as a spatial repellent that you spray around your house, and it could be used on soaps; so you come back from a walk in the woods and scrub and it gets rid of ticks. I’ve seen the kill curves, it’s at least as good as DEET. But that doesn’t mean it’s going to end up being a good product. How long it will remain in environment, whether it will break down, these are the kinds of things we have to find out.

CR: What about things like GM Mosquitoes, and other biological control strategies, that are closer to the finish line, but that many people are afraid of using?

TF: I think some of the Wollbachia and gene editing techniques for Aedes are promising. I know there are anxieties tied to the idea of “eliminating an entire species.” But Aedes aegypti is an invasive species; it doesn’t belong here. And if it were gone, we would all be better off.

Correction: An earlier version of this article mistakenly implied that polio was resurgent, rather than dengue. The reference has been changed.